One For the GM-Guru

Ok..I have a six-disc in dash bose changer. Well, I didn't put the dvd player option on the truck, and and now kicking myself for it. My question is this, forget the money problem, but are all the connections already in the truck? Is there a different wiring harness? I am pretty sure it is the same radio, but I want to have the dvd player. You know, so it says "DVD" on the screen of the radio when playing a dvd in the player. Anyway, any help would be appreciated. Thanks in advance!